I checked all gate resisters to B- and get zero volts. Checked them from zero throttle to full throttle and no change.

There is no traction pack connected. Just for the hell of it I measured across B+ and B- and I read 12.81 volts. That is more than my supply battery. Maybe it is from the caps from when 12v battery pack was connected.

Connected a 12v traction pack and checked all 10 pull-up resisters again. Zero volts between resister and B- in any position of the pot.

Ok so now we move up the pipeline until the badness reveals itself. If both leds are on solid, it is likely not a fault like current sensor not hooked up, or throttle out of range. I'll write more in a little bit. Going for walk with wife to get laundry off the line.

OK, measure the voltage from the top of R11 to the back metal face of U1 (that's a nice accessible ground). By the top of R11, I mean the side of R11 that's the furthest away from the 10 resistors GR1, ..., GR10. That's the PWM output. Measure the voltage of that at zero throttle and at full throttle. It should go from 0v up to 5v. If that's OK, the next measure the voltage from the left side of R15 to the back metal face thing of U1 at zero and full throttle. If that goes from 0v to 5v, then measure the voltage from the bottom of R16 to PH1 or PH2 (or B- bus bar).

OK good. So it's definitely not a fault from the NAND gates. The signal is making it to U6, but isn't making it to U7. Yes, I think U6 is bad. If you get a replacement, I would get the hcpl-4506 instead of hcpl-4504. That's a newer part that has a better current transfer ratio, and works a lot better.